This invention relates generally to optically-based methods and apparatus for identifying articles and, specifically, to methods and apparatus for identifying optically coded articles.
In U.S. Pat. No. 5,448,582, a multi-phase gain medium is disclosed as having an emission phase (such as dye molecules) and a scattering phase (such as TiO2). A third, matrix phase may also be provided in some embodiments. Suitable materials for the matrix phase include solvents, glasses and polymers. The gain medium is shown to provide a laser-like spectral linewidth collapse above a certain pump pulse energy. The gain medium is disclosed to be suitable for encoding objects with multiple-wavelength codes, and to be suitable for use with a number of substrate materials, including polymers and textiles.
A class of industrial problems exist in which a large number of items must be separated, identified counted and/or sorted. Present day methods cover a broad spectrum of solutions. One solution applicable to macroscopic and visually identifiable items involves a manual process wherein worker s sequentially select items from among many items in a group by identifying an intrinsic characteristic of an item or by a visually-readable coding system that is incorporated into the item. Once selected, the items are directed, either manually or by use of a conveyance, to a location where items possessing a common attribute are stored or further processed. In cases where inventory control is of interest, the selected items can be counted and tabulated either manually by some direct action by a worker or automatically as the selected item passes through a counting device.
In the commercial laundry industry, for example, rental garments are returned in unsorted groups and washed. Workers select single garments, place the garments on a hanger and subsequently onto a conveyor which deposits the garments into one of several holding areas. An appropriate one of the several holding areas is chosen for an individual garment based on a man-readable code applied onto the garment, usually inside the collar, which identifies some attribute common to all garments in a holding location. Typically, attributes include, for example, a day of the week, a route number, or an end user name similarly, in the linen supply industry, linens are delivered to a laundry in large, unsorted groups. Workers select individual linen items from a group and identify each item by a characteristics thereof, for example, color, shape and/or size. The selected and identified item is then directed to an appropriate area for washing by a specific wash formulation.
As can be appreciated, the manual labor to identify, count, sort and tabulate items (e.g., linen and/or garment items) has numerous limitations. A limitation in processing throughput is of particular interest herein. In some laundries about 100,000 or more individual items must be processed in a single 8-hour work shift. Since workers are required to perform multiple tasks on each item (e.g., identify, count and sort each item), only a limited number of items can be processed by a typical worker in an 8-hour shift. Further, the burden of manually performing multiple tasks on each item may also lead to inaccuracies in the identifying, sorting and counting processes.
In an effort to eliminate, or at least to minimize, the limitations in the manual processes outlined above, automated solutions have been sought. Conventional automated processes have been developed to improve the accuracy of and to minimize the labor required to identify, count and sort individual items. For example, bar code labels (typically interleaved 2 of 5 symbology) and Radio Frequency (RF) chips have been employed by laundries to achieve these results. These techniques, however, do have limited longevity particularly since the labels and chips are exposed to the harsh industrial laundry environment. Additionally, a solution which employs the bar coded labels suffers for it is time consuming and, at times, extremely difficult to locate a label on a large item when the label is not properly aligned with, i.e. in a field of view of, the bar code reading device. While RF chips do not suffer from the alignment problem, RF chips are troublesome due to their unproven longevity and high costs.
In the copending U.S. patent application Ser. No. 08/842,716 now U.S. Pat. No. 5,881,886, an alternate method of identifying items is disclosed. In this alternate method, photonically active materials, such as patches, labels and threads, can be affixed to garments and linens. A suitable selection of the materials each having, for example, a distinct and uniquely identifiable narrow-band lasing emission are utilized to form optically identifiable codes. The codes permit the identification of the garments, linens and other articles. In one embodiment, two or more fibers or threads, herein after referred to as LaserThread(trademark), exhibit detectable emissions that are incorporated into the garments, linens and other articles to optically encode information into these articles. For example, LaserThread(trademark) may be incorporated into garment labels for uniquely identifying a rental garment, or characteristics thereof, during processing. Similarly, LaserThread(trademark) may be sewn into borders of linens, e.g., into the hem of a table linen, for uniquely identifying linens and/or characteristics thereof.
As is noted in the above-referenced copending U.S. patent application, LaserThread(trademark) emits laser-like emissions when excited with, for example, a laser having specific. wavelength, pulse energy and pulse duration. Generally, the required excitation laser has a wavelength in the red to blue region of the visible spectrum and can provide radiant energy densities on the order of, for example, about 10 millijoules per square centimeter when an about 10 nanosecond pulse is directed at the LaserThread(trademark). Exemplary excitation sources include, for example, flashlamp-pumped, Q-switched, frequency doubled Nd:YAG lasers, diode-pumped, Q-switched, frequency-doubled Nd:YAG lasers, and sources derived from other nonlinear products involving principally Nd:YAG lasers or other laser crystals.
However, commercially available excitation sources suitable to excite photonically active materials such as, for example, LaserThread(trademark), can be costly. Therefore, it can be appreciated that an identification system design which maximizes the efficiency of excitation pulse energy is important. It can further be appreciated that the efficiency of excitation pulse energy can be maximized by tightly controlling the location and orientation of photonically active materials incorporated within an article to be evaluated. If tight controls are maintained, then a narrow excitation beam of fixed orientation can impinge on the photonically active materials incorporated within the article to be evaluated with a predictable degree of certainty. Alternatively, if the controls of the location and orientation of the photonically active materials are relaxed, then a targeting system is needed to locate the photonically active materials incorporated into the articles such that an excitation beam can be directed to excite the materials.
As was discussed above, the ability to tightly control the orientation of photonically active materials incorporated within an article under evaluation is particularly troublesome during various processing operations. For example, a region of the article containing the material may be soiled or otherwise obstructed and, thus, the irradiation of the photonically active materials is prevented. Therefore, the inventor has realized that it is advantageous to employ a targeting system and an identification system with processes for separating, identifying, counting and optionally sorting articles.
It is a first object and advantage of this invention to provide improved methods and apparatus for identifying and optionally sorting articles that overcomes the foregoing and other problems.
It is another object and advantage of this invention to provide improved methods and apparatus for identifying articles based upon an emission detected from an article.
It is a further object and advantage of this invention to provide methods and apparatus for identifying articles that includes an acquisition of luminous materials incorporated within or upon a surface of an article, a directed excitation of the luminous materials, and a detection of an emission of the luminous materials to identify and (optionally) sort the article.
Further objects and advantages of this invention will become more apparent from a consideration of the drawings and ensuing description.
The foregoing and other problems are overcome and the objects and advantages are realized by methods and apparatus in accordance with embodiments of this invention.
A method of the present invention includes steps of: (a) providing a plurality of articles to be identified, each of the articles having at least one portion that includes a photonically active material; (b) for each article; illuminating the at least one portion with light from a stimulus source; (c) identifying a location of the at least one portion by detecting an emission from the photonically active material; (d) pointing an excitation source at the identified location; (e) illuminating the at least one portion within the identified location with light from the excitation source; and (f) detecting a narrow-band laser-like or secondary emission from the photonically active material in response to the light from the excitation source. An optional step of sorting the articles based on the detected laser-like or secondary emission can also be accomplished. The detected laser-like or secondary emission conveys information in the form of an optical code for identifying at least one characteristic of the article during processing operations.
In accordance with the present invention, an apparatus for identifying articles includes a device for conveying each article through a field of view of the apparatus. A stimulus source generates light which illuminates at least one portion of the article within the field of view. In the present invention, the at least one portion includes a photonically active material. In response to the light from the stimulus source the photonically active material emits a fluorescent emission. A device identifies a location of the at least one portion by detecting the emission from the photonically active material. An excitation source generates light that exceeds a threshold fluence. A pointing device directs the excitation source at the identified location such that the light from the excitation source illuminates the at least one portion within the identified location. In response to the light from the excitation source, the photonically active material emits a narrow-band laser-like or secondary emission. An optical detector detects the narrow-band laser-like or secondary emission from the photonically active material. The detected laser-like or secondary emission conveys an optical code for identifying at least one characteristic of the article. The at least one characteristic may then be utilized to identify and to, optionally, sort the articles.